Medical systems and methods

ABSTRACT

A fluid management system for use in a tissue resection procedure includes a controller. An inflow pump is operated by the controller and configured to provide fluid inflow through a flow path to a site in patient&#39;s body. An outflow pump is operated by the controller and configured to provide fluid outflow through a flow path from the site in patient&#39;s body. A motor driven resecting device may be provided for resecting tissue at the site. The controller is configured to actuate an inflow pump and an outflow pump in response to various signals and various algorithms are provided to provide malfunction warnings and assure safe operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/887,390, filed Feb. 2, 2018; which is a continuation of U.S.application Ser. No. 14/247,649, filed Apr. 8, 2014, now U.S. Pat. No.9,907,563, which claims priority to U.S. Provisional Application61/809,681, filed on Apr. 8, 2013, the full disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to surgical fluid management systems andmethods, for example for use in distending the uterine cavity to allowresection and extraction of abnormal uterine tissue such as fibroids andpolyps.

BACKGROUND OF THE INVENTION

Uterine fibroids are non-cancerous tumors that develop in the wall ofuterus. Such fibroids occur in a large percentage of the femalepopulation, with some studies indicating up to 40 percent of all womenhave fibroids. Uterine fibroids can grow over time to be severalcentimeters in diameter and symptoms can include menorrhagia,reproductive dysfunction, pelvic pressure and pain.

One current treatment of fibroids is hysteroscopic resection ormyomectomy which involves transcervical access to the uterus with ahysteroscope together with insertion of a resecting instrument through aworking channel in the hysteroscope. The resecting instrument may be amechanical tissue cutter or an electrosurgical resection device such asa cutting loop. Mechanical cutting devices are disclosed in U.S. Pat.Nos. 7,226,459; 6,032,673 and 5,730,752 and U.S. Published PatentApplication 2009/0270898. An electrosurgical resecting device isdisclosed in U.S. Pat. No. 5,906,615.

In a myomectomy or hysteroscopic resection, the initial step of theprocedure includes distention of the uterine cavity to create a workingspace for assisting viewing through the hysteroscope. In a relaxedstate, the uterine cavity collapses with the uterine walls in contactwith one another. A fluid management system is used to distend theuterus to provide a working space wherein a fluid is administeredthrough a passageway in the hysteroscope under sufficient pressure toexpand or distend the uterine cavity. The fluids used to distend theuterus are typically liquid aqueous solutions such as a saline solutionor a sugar-based aqueous solution.

In some RF electrosurgical resection procedures, the distending fluid isa non-conductive aqueous solution to limit RF current conduction.

One particular concern is the fact that fluid management systemstypically administer the fluid under a pressure of up to 100 mm Hg ormore which results in a significant risk that the distending fluid maybe taken up by a cut blood vessel exposed in the uterine cavity. Suchunwanted fluid uptake is known as intravasation, which can lead toserious complications and even death. For this reason, fluid managementsystems have been developed to monitor the patient's fluid uptake on acontinuous basis during a procedure, typically using complicated systemsthat capture, collect and weigh distending fluids that flow through theuterine cavity.

While hysteroscopic resection can be effective in removing uterinefibroids, many commercially available instrument are too large indiameter and thus require anesthesia in an operating room environment.Conventional resectoscopes require cervical dilation to about 9 mm. Whatis needed is a system that can effectively resect and remove fibroidtissue through a small diameter hysteroscope.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a fibroid treatment systemcomprises a controller, an inflow pump operated by the controller andconfigured to provide fluid inflow through a flow path to a patient'suterine cavity, an outflow pump operated by the controller andconfigured to provide fluid outflow through a flow path to the uterinecavity and a motor driven resecting device operated by the controller.The resecting device comprises an elongate introducer member having atissue extraction channel therein with a diameter of no less than 2.4 mmand an outer sleeve having a diameter of no more than 3.8 mm. Further,the resecting device is adapted to remove fibroid tissue at a rate of atleast 2 gm/min. In one variation, the controller can be configured toactuate the inflow and outflow pumps in response to signals of fluidpressure in the uterine cavity and to maintain the target pressure asdescribed above. Additionally, the signal of fluid pressure can beprovided by a pressure sensor coupled to a static fluid columncommunicating with the uterine cavity. In another variation, thecontroller can be configured to operate the resecting device in responseto at least one parameter selected from a group consisting of an inflowpump speed, an outflow pump speed and signals of fluid pressure in theuterine cavity as will be described further below.

In a second aspect of the invention, a fluid management system comprisesa controller. A first pump is operated by the controller and configuredto provide a fluid inflow to a site in patient's body. A second pump isalso operated by the controller and configured to provide a fluidoutflow from the site in patient's body. The controller is configured tomaintain at least one operating parameter selected from a groupconsisting of a first pump speed, a fluid inflow rate, a second pumpspeed, and a fluid outflow rate, and the controller is configured toprovide a fluid loss warning if the first pump speed exceeds apredetermined level for a pre-selected time interval.

In exemplary embodiments of the second aspect, the pre-selected timeinterval may be at least 1 second, at least 5 seconds, or at least 10seconds. The controller may be further configured to de-activate atleast one pump if the first pump speed exceeds the predetermined levelfor the pre-selected time interval, and the controller may be stillfurther configured to de-activate a powered resecting device positionedin the site if the first pump speed exceeds the predetermined level forthe pre-selected time interval.

In a third aspect of the present invention, a fluid management systemcomprises a controller. An inflow pump is operated by the controller andadapted to provide a fluid inflow through a flow path to a site in apatient's body. An outflow pump is also operated by the controller andadapted to provide a fluid outflow through a flow path from the site inthe patient's body. The controller is configured to maintain at leastone operating parameter selected from a group consisting of a first pumpspeed, a fluid inflow rate, a second pump speed, and a fluid outflowrate, and the controller is configured to provide a blocked flow warningif a calculated power for driving the inflow pump exceeds apredetermined level for a pre-selected time interval.

In exemplary embodiments of the third aspect of the present invention,the controller may be further configured to de-activate at least onepump if the calculated power for driving the inflow pump exceeds thepredetermined level for the pre-selected time interval. The controllermay be still further configured to de-activate a powered resectingdevice positioned in the site if the calculated power for driving theinflow pump exceeds the predetermined level for the pre-selected timeinterval.

In a fourth aspect of the present invention, a fluid management systemcomprises a controller. A first pump is operated by the controller andconfigured to provide fluid inflow to a site in patient's body. A secondpump is also operated by the controller and configured to provide fluidoutflow from the site in patient's body. The controller is configured tomaintain at least one operating parameter selected from a groupconsisting of a first pump speed, a fluid inflow rate, a second pumpspeed, and a fluid outflow rate, and the controller is furtherconfigured to provide a blocked flow warning if an input voltage to theinflow pump motor is below a predetermined threshold voltage for apre-selected time interval.

In exemplary embodiments of the fourth aspect of the present invention,the pre-selected time interval may range from 5 seconds to 120 seconds.The controller may be further configured to de-activate at least onepump if the input voltage to the inflow pump falls below thepredetermined level for the pre-selected time interval, and thecontroller may be still further configured to de-activate the poweredresecting device positioned in the site if the voltage to the inflowpump motor exceeds the predetermined level for the pre-selected timeinterval.

In a fifth aspect of the present invention, a fluid management systemcomprises a controller. An inflow pump is operated by the controller andconfigured to provide fluid inflow through a flow path to a site inpatient's body. An outflow pump is also operated by the controller andconfigured to provide fluid outflow through a flow path from the site inpatient's body. The controller is configured to maintain at least oneoperating parameter selected from a group consisting of a first pumpspeed, a fluid inflow rate, a second pump speed, and a fluid outflowrate, and the controller is further configured to provide a blocked flowwarning if a measured current to the outflow pump exceeds apredetermined threshold voltage for a pre-selected time interval.

In a sixth aspect of the present invention, a fluid management systemfor use in a tissue resection procedure comprises a controller. Aninflow pump is operated by the controller and configured to provide afluid inflow through a flow path to a site in patient's body. An outflowpump is also operated by the controller and configured to provide afluid outflow through a flow path from the site in patient's body. Amotor driven resecting device for resecting tissue at the site is alsoprovided. The controller is configured to actuate an inflow pump and anoutflow pump in response to signals of actual pressure at the site inthe patient's body to provide respective fluid inflow and fluid outflowto maintain a target pressure at the site, and the controller is furtherconfigured to de-activate the motor driven resecting device upon sensingthat the actual pressure in the site falls below a predeterminedthreshold pressure level.

In exemplary embodiments of the sixth aspect of the present invention,the controller may be further configured to de-activate a motor in themotor driven resecting device if actual pressure in the site falls belowa predetermined threshold pressure level. The controller may bealternatively configured to de-activate at least one tissue resectingelectrode in the motor driven tissue resection device if actual pressurein the site falls below a predetermined threshold pressure level. Thethreshold pressure level is 100 mmHg or less, 50 mmHg or less, or 25mmHg or less.

In a seventh aspect of the present invention, a fluid management systemfor use in tissue resection comprises a controller. The controller isconfigured to (a) actuate an inflow pump and an outflow pump in responseto signals of actual pressure in a site in patient's body to therebyprovide respective fluid inflows and fluid outflows to maintain a targetpressure at said site, (b) send a tissue-engagement signal to thecontroller after sensing a predetermined increase in the actual pressurewithin a pre-selected interval resulting from a resecting tool engagingtargeted tissue in the site, (c) send a tissue-disengagement signal tothe controller after sensing a predetermined decrease in the actualpressure within a pre-selected interval resulting from a resecting toolsubsequently disengaging from the tissue, and (d) modulate an operatingparameter of the fluid management system in response to atissue-engagement signal or a tissue-disengagement signal.

In exemplary embodiments of the seventh aspect of the present invention,the controller may be further configured to place the inflow pump in aready state to provide a selected high inflow rate in response to atissue-engagement signal. The controller may also be configured toactuate the inflow pump to provide a selected high inflow rate inresponse to a tissue dis-engagement signal.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an assembly including a hysteroscope and atissue-resecting device corresponding to the invention that is insertedthrough the working channel of the hysteroscope.

FIG. 2 is a schematic perspective view of a fluid management system usedfor distending the uterus and for assisting in electrosurgical tissueresection and extraction.

FIG. 3 is a cross-sectional view of the shaft of the hysteroscope ofFIG. 1 showing various channels therein.

FIG. 4 is a schematic side view of the working end of theelectrosurgical tissue-resecting device of FIG. 1 showing an outersleeve and a reciprocating inner sleeve and an electrode arrangement.

FIG. 5 is a schematic perspective view of the working end of the innersleeve of FIG. 4 showing its electrode edge.

FIG. 6A is a schematic cut-away view of a portion of outer sleeve, innerRF resecting sleeve and a tissue-receiving window of the outer sleeve.

FIG. 6B is a schematic view of a distal end portion another embodimentof inner RF resecting sleeve.

FIG. 7A is a cross sectional view of the inner RF resecting sleeve ofFIG. 6B taken along line 7A-7A of FIG. 6B.

FIG. 7B is another cross sectional view of the inner RF resecting sleeveof FIG. 6B taken along line 7B-7B of FIG. 6B.

FIG. 8 is a schematic view of a distal end portion of another embodimentof inner RF resecting sleeve.

FIG. 9A is a cross sectional view of the RF resecting sleeve of FIG. 8taken along line 9A-9A of FIG. 8 .

FIG. 9B is a cross sectional view of the RF resecting sleeve of FIG. 8taken along line 9B-9B of FIG. 8 .

FIG. 10A is a perspective view of the working end of thetissue-resecting device of FIG. 1 with the reciprocating RF resectingsleeve in a non-extended position.

FIG. 10B is a perspective view of the tissue-resecting device of FIG. 1with the reciprocating RF resecting sleeve in a partially extendedposition.

FIG. 10C is a perspective view of the tissue-resecting device of FIG. 1with the reciprocating RF resecting sleeve in a fully extended positionacross the tissue-receiving window.

FIG. 11A is a sectional view of the working end of the tissue-resectingdevice of FIG. 10A with the reciprocating RF resecting sleeve in anon-extended position.

FIG. 11B is a sectional view of the working end of FIG. 10B with thereciprocating RF resecting sleeve in a partially extended position.

FIG. 11C is a sectional view of the working end of FIG. 10C with thereciprocating RF resecting sleeve in a fully extended position.

FIG. 12A is an enlarged sectional view of the working end oftissue-resecting device of FIG. 11B with the reciprocating RF resectingsleeve in a partially extended position showing the RF field in a firstRF mode and plasma resecting of tissue.

FIG. 12B is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF resecting sleeve almost fully extended andshowing the RF fields switching to a second RF mode from a first RF modeshown in FIG. 12 .

FIG. 12C is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF resecting sleeve again almost fully extendedand showing the explosive vaporization of a captured liquid volume toexpel resected tissue in the proximal direction.

FIG. 13 is an enlarged perspective view of a portion of the working endof FIG. 12C showing an interior chamber and a fluted projecting element.

FIG. 14 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element.

FIG. 15 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element configured toexplosively vaporize the captured liquid volume.

FIG. 16 is a schematic view of a system for fibroid removal including afluid management system.

FIG. 17 is a schematic view of the fluid management system of FIG. 16with an enlarged view of the working end of a tissue-resecting probe asgenerally described in FIGS. 1-12C in a position to resect and extractfibroid tissue.

FIG. 18 is a schematic view of a pressure sensor component of the fluidmanagement system of FIGS. 16-17 .

FIG. 19 is a cut-away schematic view of a filter module of the fluidmanagement system of FIGS. 16-17 .

FIG. 20 is a schematic view of an endoscope and fluid management systembeing used in a diagnostic mode.

FIG. 21 is a schematic view of the endoscope and fluid management systemof FIG. 20 together with a resecting probe with the assembly as used isa non-diagnostic or therapeutic mode.

DETAILED DESCRIPTION

FIG. 1 illustrates an assembly that comprises an endoscope 50 used forhysteroscopy together with a tissue resecting device 100 extendingthrough a working channel 102 of the endoscope. The endoscope orhysteroscope 50 has a handle 104 coupled to an elongated shaft 105having a diameter of 5 mm to 7 mm. The working channel 102 therein maybe round, D-shaped or any other suitable shape. The endoscope shaft 105is further configured with an optics channel 106 and one or more fluidinflow/outflow channels 108 a, 108 b (FIG. 3 ) that communicate withvalve-connectors 110 a, 110 b configured for coupling to a fluid inflowsource 120 thereto, or optionally a negative pressure source 125 (FIGS.1-2 ). The fluid inflow source 120 is a component of a fluid managementsystem 126 as is known in the art (FIG. 2 ) which comprises a fluidcontainer 128 and pump mechanism 130 which pumps fluid through thehysteroscope 50 into the uterine cavity. As can be seen in FIG. 2 , thefluid management system 126 further includes the negative pressuresource 125 (which can comprise an operating room wall suction source)coupled to the tissue-resecting device 100. The handle 104 of theendoscope includes the angled extension portion 132 with optics to whicha videoscopic camera 135 can be operatively coupled. A light source 136also is coupled to light coupling 138 on the handle of the hysteroscope50. The working channel 102 of the hysteroscope is configured forinsertion and manipulation of the tissue-resecting and extracting device100, for example to treat and remove fibroid tissue. In one embodiment,the hysteroscope shaft 105 has an axial length of 21 cm, and cancomprise a 0° scope, or 15° to 30° scope.

Still referring to FIG. 1 , the tissue-resecting device 100 has a highlyelongated shaft assembly 140 configured to extend through the workingchannel 102 in the hysteroscope. A handle 142 of the tissue-resectingdevice 100 is adapted for manipulating the electrosurgical working end145 of the device. In use, the handle 142 can be manipulated bothrotationally and axially, for example, to orient the working end 145 toresect targeted fibroid tissue. The tissue-resecting device 100 hassubsystems coupled to its handle 142 to enable electrosurgical resectingof targeted tissue. A radiofrequency generator or RF source 150 andcontroller 155 are coupled to at least one RF electrode carried by theworking end 145 as will be described in detail below. In one embodimentshown in FIG. 1 , an electrical cable 156 and negative pressure source125 are operatively coupled to a connector 158 in handle 142. Theelectrical cable couples the RF source 150 to the electrosurgicalworking end 145. The negative pressure source 125 communicates with atissue extraction channel 160 in the shaft assembly 140 of the tissueextraction device 100 (FIG. 4 ).

FIG. 1 further illustrates a seal housing 162 that carries a flexibleseal 164 carried by the hysteroscope handle 104 for sealing the shaft140 of the tissue-resecting device 100 in the working channel 102 toprevent distending fluid from escaping from a uterine cavity.

In one embodiment as shown in FIG. 1 , the handle 142 oftissue-resecting device 100 includes a motor drive 165 for reciprocatingor otherwise moving a resecting component of the electrosurgical workingend 145 as will be described below. The handle 142 optionally includesone or more actuator buttons 166 for actuating the device. In anotherembodiment, a footswitch can be used to operate the device. In oneembodiment, the system includes a switch or control mechanism to providea plurality of reciprocation speeds, for example 1 Hz, 2 Hz, 3 Hz, 4 Hzand up to 8 Hz. Further, the system can include a mechanism for movingand locking the reciprocating resecting sleeve in a non-extendedposition and in an extended position. Further, the system can include amechanism for actuating a single reciprocating stroke.

Referring to FIGS. 1 and 4 , an electrosurgical tissue resecting devicehas an elongate shaft assembly 140 extending about longitudinal axis 168comprising an exterior or first outer sleeve 170 with passageway orlumen 172 therein that accommodates a second or inner sleeve 175 thatcan reciprocate (and optionally rotate or oscillate) in lumen 172 toresect tissue as is known in that art of such tubular cutters. In oneembodiment, the tissue-receiving window 176 in the outer sleeve 170 hasan axial length ranging between 10 mm and 30 mm and extends in a radialangle about outer sleeve 170 from about 45° to 210° relative to axis 168of the sleeve. The outer and inner sleeves 170 and 175 can comprise athin-wall stainless steel material and function as opposing polarityelectrodes as will be described in detail below. FIGS. 6A-8 illustrateinsulative layers carried by the outer and inner sleeves 170 and 175 tolimits, control and/or prevent unwanted electrical current flows betweencertain portions go the sleeve. In one embodiment, a stainless steelouter sleeve 170 has an O.D. of 3.6 mm to 3.8 mm with an I.D. of 3.38 mmto 3.5 mm and with an inner insulative layer (described below) thesleeve has a nominal I.D. of about 3.175 mm″. In this embodiment, thestainless steel inner sleeve 175 has an O.D. of about 3.05 mm with anI.D. of about 2.84 mm″. The inner sleeve 175 with an outer insulativelayer has a nominal O.D. of about 3.12 mm″ to reciprocate in lumen 172.The inner diameters of the inner sleeve portions are described below. Ascan be seen in FIG. 4 , the distal end 177 of inner sleeve 175 comprisesa first polarity electrode with distal resecting electrode edge 180about which plasma can be generated. The electrode edge 180 also can bedescribed as an active electrode during tissue resecting since theelectrode edge 180 then has a substantially smaller surface area thanthe opposing polarity or return electrode. In one embodiment in FIG. 4 ,the exposed surfaces of outer sleeve 170 comprises the second polarityelectrode 185, which thus can be described as the return electrode sinceduring use such an electrode surface has a substantially larger surfacearea compared to the functionally exposed surface area of the activeelectrode edge 180.

In one aspect of the invention, the inner sleeve or resecting sleeve 175has an interior tissue extraction lumen 160 with first and secondinterior diameters that are adapted to electrosurgically resect tissuevolumes rapidly—and thereafter consistently extract the resected tissuestrips through the highly elongated lumen 160 without clogging. Nowreferring to FIGS. 5 and 6A, it can be seen that the inner sleeve 175has a first diameter portion 190A that extends from the handle 142 (FIG.1 ) to a distal region 192 of the sleeve 175 wherein the tissueextraction lumen transitions to a smaller second diameter lumen 190Bwith a reduced diameter indicated at B which is defined by the electrodesleeve element 195 that provides resecting electrode edge 180. The axiallength C of the reduced cross-section lumen 190B can range from about 2mm to 20 mm. In one embodiment, the first diameter A is between 2.8 mmand 2.9 mm and the second reduced diameter B is between 2.4 mm and 2.5mm. As shown in FIG. 5 , the inner sleeve 175 can be an electricallyconductive stainless steel and the reduced diameter electrode portionalso can comprise a stainless steel electrode sleeve element 195 that iswelded in place by weld 196 (FIG. 6A). In another alternativeembodiment, the electrode and reduced diameter electrode sleeve element195 comprises a tungsten tube that can be press fit into the distal end198 of inner sleeve 175. FIGS. 5 and 6A further illustrates theinterfacing insulation layers 202 and 204 carried by the first andsecond sleeves 170, 175, respectively. In FIG. 6A, the outer sleeve 170is lined with a thin-wall insulative material 200, such as PFA, oranother material described below. Similarly, the inner sleeve 175 has anexterior insulative layer 202. These coating materials can be lubriciousas well as electrically insulative to reduce friction duringreciprocation of the inner sleeve 175.

The insulative layers 200 and 202 described above can comprise alubricious, hydrophobic or hydrophilic polymeric material. For example,the material can comprise a bio-compatible material such as PFA,TEFLON®, polytetrafluroethylene (PTFE), FEP (Fluorinatedethylenepropylene), polyethylene, polyamide, ECTFE(Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride orsilicone.

Now turning to FIG. 6B, another variation of inner sleeve 175 isillustrated in a schematic view together with a tissue volume beingresected with the plasma electrode edge 180. In this embodiment, as inother embodiments in this disclosure, the RF source operates at selectedoperational parameters to create a plasma around the electrode edge 180of electrode sleeve 195 as is known in the art. Thus, the plasmagenerated at electrode edge 180 can resect and ablate a path P in thetissue 220, and is suited for resecting fibroid tissue and otherabnormal uterine tissue. In FIG. 6B, the distal portion of the resectingsleeve 175 includes a ceramic collar 222 which is adjacent the distaledge 180 of the electrode sleeve 195. The ceramic 222 collar functionsto confine plasma formation about the distal electrode edge 180 andfunctions further to prevent plasma from contacting and damaging thepolymer insulative layer 202 on the resecting sleeve 175 duringoperation. In one aspect of the invention, the path P cut in the tissue220 with the plasma at electrode edge 180 provides a path P having anablated width indicated at W, wherein such path width W is substantiallywide due to tissue vaporization. This removal and vaporization of tissuein path P is substantially different than the effect of cutting similartissue with a sharp blade edge, as in various prior art devices. A sharpblade edge can divide tissue (without cauterization) but appliesmechanical force to the tissue and may prevent a large cross sectionslug of tissue from being cut. In contrast, the plasma at the electrodeedge 180 can vaporize a path P in tissue without applying anysubstantial force on the tissue to thus resect larger cross sections orslugs strips of tissue. Further, the plasma resecting effect reduces thecross section of tissue strip 225 received in the tissue-extractionlumen 190B. FIG. 6B depicts a tissue strip to 225 entering lumen 190Bwhich has such a smaller cross-section than the lumen due to thevaporization of tissue. Further, the cross section of tissue 225 as itenters the larger cross-section lumen 190A results in even greater freespace 196 around the tissue strip 225. Thus, the resection of tissuewith the plasma electrode edge 180, together with the lumen transitionfrom the smaller cross-section (190B) to the larger cross-section (190A)of the tissue-extraction lumen 160 can significantly reduce or eliminatethe potential for successive resected tissue strips 225 to clog thelumen. Prior art resection devices with such small diameter tissueextraction lumen typically have problems with tissue clogging.

In another aspect of the invention, the negative pressure source 225coupled to the proximal end of tissue extraction lumen 160 (see FIGS. 1and 4 ) also assists in aspirating and moving tissue strips 225 in theproximal direction to a collection reservoir (not shown) outside thehandle 142 of the device.

FIGS. 7A-7B illustrate the change in lumen diameter of resecting sleeve175 of FIG. 6B. FIG. 8 illustrates the distal end of a variation ofresecting sleeve 175′ which is configured with an electrode resectingelement 195′ that is partially tubular in contrast to the previouslydescribed tubular electrode element 195 (FIGS. 5 and 6A). FIGS. 9A-9Bagain illustrate the change in cross-section of the tissue extractionlumen between reduced cross-section region 190B′ and the increasedcross-section region 190A′ of the resecting sleeve 175′ of FIG. 8 .Thus, the functionality remains the same whether the resecting electrodeelement 195′ is tubular or partly tubular. In FIG. 8A, the ceramiccollar 222′ is shown, in one variation, as extending only partiallyaround sleeve 175 to cooperate with the radial angle of resectingelectrode element 195′. Further, the variation of FIG. 8 illustratesthat the ceramic collar 222′ has a larger outside diameter thaninsulative layer 202. Thus, friction may be reduced since the shortaxial length of the ceramic collar 222′ interfaces and slides againstthe interfacing insulative layer 200 about the inner surface of lumen172 of outer sleeve 170.

In general, one aspect of the invention comprises a tissue resecting andextracting device (FIGS. 10A-11C) that includes first and secondconcentric sleeves having an axis and wherein the second (inner) sleeve175 has an axially-extending tissue extraction lumen therein, andwherein the second sleeve 175 is moveable between axially non-extendedand extended positions relative to a tissue receiving window 176 infirst sleeve 170 to resect tissue, and wherein the tissue extractionlumen 160 has first and second cross-sections. The second sleeve 175 hasa distal end configured as a plasma electrode edge 180 to resect tissuedisposed in tissue receiving window 176 of the first sleeve 170.Further, the distal end of the second sleeve, and more particularly, theelectrode edge 180 is configured for plasma ablation of a substantiallywide path in the tissue. In general, the tissue extraction device isconfigured with a tissue extraction lumen 160 having a distal endportion with a reduced cross-section that is smaller than across-section of medial and proximal portions of the lumen 160.

In one aspect of the invention, referring to FIGS. 7A-7B and 9A-9B, thetissue extraction lumen 160 has a reduced cross-sectional area in lumenregion 190A proximate the plasma resecting tip or electrode edge 180wherein said reduced cross section is less that 95%, 90%, 85% or 80%than the cross sectional area of medial and proximal portions 190B ofthe tissue extraction lumen, and wherein the axial length of the tissueextraction lumen is at least 10 cm, 20 cm, 30 cm or 40 cm. In oneembodiment of tissue resecting device 100 for hysteroscopic fibroidresecting and extraction (FIG. 1 ), the shaft assembly 140 of the tissueresecting device is 35 cm in length.

FIGS. 10A-10C illustrate the working end 145 of the tissue resectingdevice 100 with the reciprocating resecting sleeve or inner sleeve 175in three different axial positions relative to the tissue receivingwindow 176 in outer sleeve 170. In FIG. 10A, the resecting sleeve 175 isshown in a retracted or non-extended position in which the sleeve 175 isat it proximal limit of motion and is prepared to advance distally to anextended position to thereby electrosurgically resect tissue positionedin and/or suctioned into in window 176. FIG. 10B shows the resectingsleeve 175 moved and advanced distally to a partially advanced or medialposition relative to tissue resecting window 176. FIG. 10C illustratesthe resecting sleeve 175 fully advanced and extended to the distal limitof its motion wherein the plasma resecting electrode 180 has extendedpast the distal end 226 of tissue receiving window 176 at which momentthe resected tissue strip 225 in excised from tissue volume 220 andcaptured in reduced cross-sectional lumen region 190A.

Now referring to FIGS. 10A-10C and FIGS. 11A-11C, another aspect of theinvention comprises “tissue displacement” mechanisms provided bymultiple elements and processes to “displace” and move tissue strips 225in the proximal direction in lumen 160 of resecting sleeve 175 to thusensure that tissue does not clog the lumen of the inner sleeve 175. Ascan seen in FIG. 10A and the enlarged views of FIGS. 11A-11C, one tissuedisplacement mechanism comprises a projecting element 230 that extendsproximally from distal tip 232 which is fixedly attached to outer sleeve170. The projecting element 230 extends proximally along central axis168 in a distal chamber 240 defined by outer sleeve 170 and distal tip232. In one embodiment depicted in FIG. 11A, the shaft-like projectingelement 230, in a first functional aspect, comprises a mechanical pusherthat functions to push a captured tissue strip 225 proximally from thesmall cross-section lumen 190B of resecting sleeve 175 as the resectingsleeve 175 moves to its fully advanced or extended position. In a secondfunctional aspect, the chamber 240 in the distal end of sleeve 170 isconfigured to capture a volume of saline distending fluid 244 from theworking space, and wherein the existing RF electrodes of the working end145 are further configured to explosively vaporize the captured fluid244 to generate proximally-directed forces on tissue strips 225 resectedand disposed in lumen 160 of the resecting sleeve 175. Both of these twofunctional elements and processes (tissue displacement mechanisms) canapply a substantial mechanical force on the captured tissue strips 225by means of the explosive vaporization of liquid in chamber 240 and canfunction to move tissue strips 225 in the proximal direction in thetissue extraction lumen 160. It has been found that using thecombination of multiple functional elements and processes can virtuallyeliminate the potential for tissue clogging the tissue extraction lumen160.

More in particular, FIGS. 12A-12C illustrate sequentially the functionalaspects of the tissue displacement mechanisms and the explosivevaporization of fluid captured in chamber 240. In FIG. 12A, thereciprocating resecting sleeve 175 is shown in a medial positionadvancing distally wherein plasma at the resecting electrode edge 180 isresecting a tissue strip 225 that is disposed within lumen 160 of theresecting sleeve 175. In FIG. 12A-12C, it can be seen that the systemoperates in first and second electrosurgical modes corresponding to thereciprocation and axial range of motion of resecting sleeve 175 relativeto the tissue receiving window 176. As used herein, the term“electrosurgical mode” refers to which electrode of the two opposingpolarity electrodes functions as an “active electrode” and whichelectrode functions as a “return electrode”. The terms “activeelectrode” and “return electrode” are used in accordance with conventionin the art—wherein an active electrode has a smaller surface area thanthe return electrode which thus focuses RF energy density about such anactive electrode. In the working end 145 of FIGS. 10A-11C, the resectingelectrode element 195 and its resecting electrode edge 180 must comprisethe active electrode to focus energy about the electrode to generate theplasma for tissue resecting. Such a high-intensity, energetic plasma atthe electrode edge 180 is needed throughout stroke X indicated in FIG.12A-12B to resect tissue. The first mode occurs over an axial length oftravel of inner resecting sleeve 175 as it crosses the tissue receivingwindow 176, at which time the entire exterior surface of outer sleeve170 comprises the return electrode indicated at 185. The electricalfields EF of the first RF mode are indicated generally in FIG. 12A.

FIG. 12 B illustrates the moment in time at which the distal advancementor extension of inner resecting sleeve 175 entirely crossed the tissuereceiving window 176. At this time, the electrode sleeve 195 and itselectrode edge 180 are confined within the mostly insulated-wall chamber240 defined by the outer sleeve 170 and distal tip 232. At this moment,the system is configured to switch to the second RF mode in which theelectric fields EF switch from those described previously in the firstRF mode. As can be seen in FIG. 12B, in this second mode, the limitedinterior surface area 250 of distal tip 232 that interfaces chamber 240functions as an active electrode and the distal end portion of resectingsleeve 175 exposed to chamber 240 acts as a return electrode. In thismode, very high energy densities occur about surface 250 and such acontained electric field EF can explosively and instantly vaporize thefluid 244 captured in chamber 240. The expansion of water vapor can bedramatic and can thus apply tremendous mechanical forces and fluidpressure on the tissue strip 225 to move the tissue strip in theproximal direction in the tissue extraction lumen 160. FIG. 12Cillustrates such explosive or expansive vaporization of the distentionfluid 244 captured in chamber 240 and further shows the tissue strip 225being expelled in the proximal direction the lumen 160 of innerresecting sleeve 175. FIG. 14 further shows the relative surface areasof the active and return electrodes at the extended range of motion ofthe resecting sleeve 175, again illustrating that the surface area ofthe non-insulated distal end surface 250 is small compared to surface255 of electrode sleeve which comprises the return electrode.

Still referring to FIGS. 12A-12C, it has been found that a single powersetting on the RF source 150 and controller 155 can be configured both(i) to create plasma at the electrode resecting edge 180 of electrodesleeve 195 to resect tissue in the first mode, and (ii) to explosivelyvaporize the captured distention fluid 244 in the second mode. Further,it has been found that the system can function with RF mode-switchingautomatically at suitable reciprocation rates ranging from 0.5 cyclesper second to 8 or 10 cycles per second. In trial, it has been foundthat the tissue resecting device described above can resect and extracttissue at the rate of from 2 grams/min to 8 grams/min without anypotential for tissue strips 225 clogging the tissue extraction lumen160. In one embodiment, a negative pressure source 125 can be coupled tothe tissue extraction lumen 160 to apply tissue-extracting forces totissue strips in the lumen.

Of particular interest, the fluid-capture chamber 240 defined by sleeve170 and distal tip 232 can be designed to have a selected volume,exposed electrode surface area, length and geometry to optimize theapplication of expelling forces to resected tissue strips 225. In oneembodiment, the diameter of the chamber is 3.175 mm and the length is5.0 mm which taking into account the projecting element 230, provided acaptured fluid volume of approximately 0.040 mL. In other variations,the captured fluid volume can range from 0.004 to 0.080 mL.

In one example, a chamber 240 with a captured liquid volume of 0.040 mLtogether with 100% conversion efficiency in an instantaneousvaporization would require 103 Joules to heat the liquid from roomtemperature to water vapor. In operation, since a Joule is a W*s, andthe system reciprocate at 3 Hz, the power required would be on the orderof 311 W for full, instantaneous conversion to water vapor. Acorresponding theoretical expansion of 1700× would occur in the phasetransition, which would results in up to 25,000 psi instantaneously(14.7 psi×1700), although due to losses in efficiency andnon-instantaneous expansion, the actual pressures would be less. In anyevent, the pressures are substantial and can apply expelling forcessufficient to the expel the captured tissue strips 225 the length of theextraction channel in the probe.

Referring to FIG. 12A, the interior chamber 240 can have an axial lengthfrom about 0.5 mm to 10 mm to capture a liquid volume ranging from about0.004 mL to 0.010 mL. It can be understood in FIG. 12A, that theinterior wall of chamber 240 has an insulator layer 200 which thuslimits the electrode surface area 250 exposed to chamber 240. In oneembodiment, the distal tip 232 is stainless steel and is welded to outersleeve 170. The post element 248 is welded to tip 232 or machined as afeature thereof. The projecting element 230 in this embodiment is anon-conductive ceramic. FIG. 13 shows the cross-section of the ceramicprojecting element 230 which is fluted, which in one embodiment hasthree flute elements 260 in three corresponding axial grooves 262 in itssurface. Any number of flutes, channels or the like is possible, forexample from 2 to about 20. The purpose of this design is to provide asignificant cross-sectional area at the proximal end of the projectingelement 230 to push the tissue strip 225, while at the same time thethree grooves 262 permit the proximally-directed jetting of water vaporto impact the tissue exposed to the grooves 262. In one embodiment, theaxial length D of the projecting element 230 is configured to pushtissue entirely out of the reduced cross-sectional region 190B of theelectrode sleeve element 195. In another embodiment, the volume of thechamber 240 is configured to capture liquid that when explosivelyvaporized provided a gas (water vapor) volume sufficient to expand intoand occupy at least the volume defined by a 10% of the total length ofextraction channel 160 in the device, at least 20% of the extractionchannel 160, at least 40% of the extraction channel 160, at least 60% ofthe extraction channel 160, at least 80% of the extraction channel 160or at least 100% of the extraction channel 160.

As can be understood from FIGS. 12A to 12C, the distention fluid 244 inthe working space replenishes the captured fluid in chamber 240 as theresecting sleeve 175 moves in the proximal direction or towards itsnon-extended position. Thus, when the resecting sleeve 175 again movesin the distal direction to resect tissue, the interior chamber 240 isfilled with fluid 244 which is then again contained and is thenavailable for explosive vaporization as described above when theresecting sleeve 175 closes the tissue receiving window 176. In anotherembodiment, a one-way valve can be provided in the distal tip 232 todraw fluid directly into interior chamber 240 without the need for fluidto migrate through window 176.

FIG. 15 illustrates another variation in which the active electrodesurface area 250′ in the second mode comprises a projecting element 230with conductive regions and non-conductive regions 260 which can havethe effect of distributing the focused RF energy delivery over aplurality of discrete regions each in contact with the captured fluid244. This configuration can more efficiently vaporize the captured fluidvolume in chamber 240. In one embodiment, the conductive regions 250′can comprise metal discs or washers on post 248. In other variation (notshown) the conductive regions 250′ can comprise holes, ports or pores ina ceramic material 260 fixed over an electrically conductive post 248.

In another embodiment, the RF source 150 and controller 155 can beprogrammed to modulate energy delivery parameters during stroke X andstroke Y in FIGS. 12A-12C to provide the optimal energy (i) for plasmaresecting with electrode edge 180, and (ii) for explosively vaporizingthe captured fluid in chamber 240. In one variation, the controller 155can include an algorithm that activates the RF source 150 to delivery RFenergy to working end as the resecting sleeve 175 moves in the distaldirection towards its extended position to resect tissue but terminatesRF energy delivery to the working end as the resecting sleeve 175 movesin the proximal direction towards its non-extended position. Thetermination of RF energy delivery during the proximal stroke of theresecting sleeve 175 eliminates energy delivery to electrode edge 180when it is not resecting tissue which thus prevents unnecessary heatingof distention fluid which would occur when RF energy is delivered duringboth the forward and backward strokes of the resecting sleeve.

FIGS. 16-18 illustrate a fluid management system 500 that can be usedwhen treating tissue in a body cavity, space or potential space 502(FIG. 17 ). The fluid management system 500 is depicted schematically ina hysteroscopic tissue resecting system 510 that is adapted forresecting and extraction of fibroids or other abnormal intra-uterinetissue using an endoscope or hysteroscope 512 and tissue resecting probe515 that can be similar to those described above. FIG. 16 depicts thetissue resecting probe 515 with handle 516 and extending memberincluding outer sleeve 518 with working end 520 (FIG. 17 ) that can beintroduced through working channel 522 extending through the body 523and shaft 524 of the hysteroscope 512. FIG. 16 further shows a motor 525in handle 516 of the tissue resecting probe that is coupled to acontroller and power supply by power cable 526. FIG. 17 illustrates theworking end 520 of the resecting probe 515 in a uterine cavity proximatea targeted fibroid 530.

Referring to FIGS. 16-17 , in general, the fluid management system 500comprises a fluid source or reservoir 535 of a distention fluid 244, acontroller and pump system to provide fluid inflows and outflows adaptedto maintain distension of a body space and a filter system 540 forfiltering distention fluid 244 that is removed from the body cavity andthereafter returned to the fluid source 535. The use of a recovered andfiltered fluid 244 and the replenishment of the fluid source 535 isadvantageous because (i) the closed-loop fluid management system caneffectively measure fluid deficit to thereby monitor intravasation andinsure patient safety, (ii) the system can be set up and operated in avery time-efficient manner, and (ii) the system can be compact and lessexpensive to thereby assist in enabling office-based procedures.

The fluid management system 500 (FIG. 16 ) includes a computer controlsystem that is integrated with the RF control system in an integratedcontroller 545. The controller 545 is adapted to control first andsecond peristaltic pumps 546A and 546B for providing inflows andoutflows of a distention fluid 244, such as saline solution, from source535 for the purpose of distending the body cavity. The first peristalticpump may also be called an inflow pump or infusion pump herein. Thesecond peristaltic pump may also be called an outflow pump or aspirationpump herein. The controller 545 and control algorithms are adapted tocontrol the intra-cavity pressure during a tissue resecting andextracting procedure as depicted in FIG. 17 . In one embodiment shown inFIGS. 16-18 , the controller 545 controls the inflow pump 546A toprovide positive pressure at the outflow side 548 of the pump (FIG. 17 )to provide inflows of distention fluid 244 through inflow line 550 whichis in communication with fitting 561 and fluid flow channel 108 a inhysteroscope 515. The flow channel 108 a is described above in aprevious embodiment and is illustrated in FIG. 3 above. The controller545 further controls the outflow pump 546B to provide negative pressureto the outflow line 555 at the inflow side 552 of the pump (FIG. 17 ) toprovide outflows of distention fluid 244 from the body cavity 502. Asdescribed above, the explosive vaporization of fluid in the working end525 of resecting probe 515 functions to expel tissue strips 225proximally in the extraction channel 160 of resecting sleeve 175, whichcan operate in conjunction with negative pressure in line 555 providedby pump 546B. In operation, the outflow pump 546B also operates toprovide positive pressure on the outflow side 556 of pump 546B in thesecond outflow line portion 555′ to pump outflows of distention fluid244 through the filter system 540 and back to the fluid source 535.

In one system embodiment, the controller 545 operates to controlpressure in cavity 502 by pressure signals from a pressure sensor 560that is coupled to a fitting 562 in hysterocope 512 which communicateswith a flow channel 108 b (see FIG. 16 ) that extends through thehysteroscope. In one embodiment, the flow channel 108 b has a diameterof at least 1.0 mm to allow highly accurate sensing of actualintra-cavity pressure. In prior art commercially-available fluidmanagement systems, the intra-cavity pressure is typically estimated byvarious calculations using known flow rates through a pump or remotepressure sensors in the fluid inflow line that can measure backpressures. Such prior art fluid management systems are stand-alonesystems and are adapted for use with a wide variety of hysteroscopes andendoscopes, most of which do not have a dedicated flow channel forcommunicating with a pressure sensor. For this reason, prior art fluidmanagement systems rely on algorithms and calculations to only estimateintra-cavity pressure.

In one embodiment, as depicted in FIG. 16 , the pressure sensor 560 isdisposable and is detachably coupled to the endoscope 512 and is influid communication with the body cavity through a flow channel 108 b inthe endoscope. The pressure sensor 560 is operatively coupled tocontroller 545 by cable 564. The pressure sensor can be a biocompatible,piezoresistive silicon sensor of the type used in invasive bloodpressure monitoring. For example, the sensor can be a piezoresistivesilicon pressure sensor, Model No. 1620, available from MeasurementSpecialties. Ltd., 45738 Northport Loop West, Fremont, Calif. 94538. Thesensor is designed with a pressure sensing element mounted on a ceramicsubstrate. A dielectric gel can be placed over the sensor element toprovide electrical and fluid isolation. The sensor housing can have aLuer connection to couple to the endoscope 512. Further, the sensor bodycan have a pressure relief valve for redundant overpressure protection(not shown).

As can be understood from FIGS. 16 and 17 , the pressure sensor 560 isattached to the endoscope 512 to communicate with a fluid channelextending through the endoscope shaft to the body cavity. The fluidchannel or sensor channel 108 b used by the pressure sensor 560 isindependent of flow channel 108 a used for distention fluid inflows intothe body cavity. In the absence of fluid flows in the sensor channel 108b, the fluid in the channel 108 b then forms a static column ofincompressible fluid that changes in pressure as the pressure in thebody cavity changes. With a sensor channel cross-section of 1 mm ormore, the pressure within the pressure channel column and the pressurein the body cavity are equivalent. Thus, the pressure sensor 560 iscapable of a direct measurement of pressure within the body cavity. Inanother variation shown schematically in FIG. 18 , the pressure sensor560 as indicated in FIG. 16 can consist of two independent sensingelements 560′ and 560″ that both interface with fluid extending into thesensor 560 from the single fluid channel 108 b. The sensing elements560′ and 560″ send pressure signals to controller 545 through cables564′ and 564″ (FIG. 18 ). At the initiation of a procedure, or during aprocedure, the controller then can be configured to monitor or comparepressure signals from the independent sensing elements 560′ and 560″. Ifthe two sensors' pressure signals are not within a preselected rangefrom one another, the controller 545 can provide a warning of sensormalfunction and/or terminate or modulate any ongoing operation of thefluid management system or resection device.

FIG. 17 schematically illustrates the fluid management system 500 inoperation. The uterine cavity 502 is a potential space and needs to bedistended to allow for hysteroscopic viewing. A selected pressure can beset in the controller 545, for example via a touch screen 565, which thephysician knows from experience is suited for distending the cavity 502and/or for performing a procedure. In one embodiment, the selectedpressure can be any pressure between 0 and 150 mm Hg. In one systemembodiment, the inflow pump 546A can operate as a variable speed pumpthat is actuated to provide a flow rate of up to 850 ml/min throughfirst line or inflow line 550. In this embodiment, the outflow pump 546Bcan operate at a fixed speed to move fluid in the second line or outflowline 555. In use, the controller 545 can operate the pumps 546A and 546Bat selected matching or non-matching speeds to increase, decrease ormaintain the volume of distention fluid 244 in the uterine cavity 502.Thus, by independent control of the pumping rates of the inflow andoutflow pumps 546A and 546B, a selected set pressure in the body cavitycan be achieved and maintained in response to signals of actualintra-cavity pressure provided by sensor 560.

In one system embodiment, as shown in FIGS. 17 and 19 , the fluidmanagement system 500 includes a filter module or system 540 that caninclude a first filter or tissue capturing filter 570 that is adapted tocatch tissue strips 225 that have been resected and extracted from thebody cavity 502. A second filter or molecular filter 575, typically ahollow fiber filter, is provided beyond the first filter 570, whereinthe molecular filter 575 is adapted to remove blood and other bodymaterials from the distention fluid 244. In particular, the molecularfilter 575 is capable of removing red blood cells, hemoglobin,particulate matter, proteins, bacteria, viruses and the like from thedistention fluid 244 so that endoscopic viewing of the body cavity isnot obscured or clouded by any such blood components or othercontaminants. As can be understood from FIGS. 16-19 , the outflow pump546B at its outflow side 556 provides a positive pressure relative tofluid flows into the filter module 540 to move the distention fluid 244and body media through the first and second filters, 570 and 575, and ina circulatory flow back to the fluid source 535.

Referring to FIG. 19 , in an embodiment, the first filter 570 comprisesa container portion or vial 576 with a removable cap 577. The inflow ofdistention fluid 244 and body media flows though line portion 555 andthrough fitting 578 into a mesh sac or perforate structure 580 disposedin the interior chamber 582 of the vial 576. The pore size of theperforate structure 580 can range from about 200 microns to 10 microns.The lumen diameter of hollow fibers 585 in the second filter 575 can befrom about 400 microns to 20 microns. In general, the pore size ofperforate structure 580 in the first filter 570 is less than thediameter of the lumens of hollow fibers 585 in the second filter 575. Inone embodiment, the pore size of the perforate structure 580 is 100microns, and the lumen size of the hollow fibers 585 in the molecularfilter 575 is 200 microns. In one embodiment, the molecular filter 575is a Nephros DSU filter available from Nephros, Inc., 41 Grand Ave.,River Edge, N.J. 07661. In one variation, the filter 575 is configuredwith hollow fibers having a nominal molecular weight limit (NMWL) ofless than 50 kDa, 30 kDa or 20 kDa.

In another aspect of the invention, the molecular filter 575 isconfigured to filter large volumes of distention fluid, since the fluidflows are circulating. Additionally, the molecular filter 575 isconfigured to filter significant potential volumes of distention fluidthat may contaminated with blood, blood products and the like that willbe mixed with the fluid. In one embodiment, the molecular filter 575 hasa membrane surface area of at least 0.6 m², 0.8 m², 1.0 m², 1.2 m² and1.4 m², wherein the membrane surface area is defined as the totalsurface area of the lumens of the hollow fibers 585 in the molecularfilter 575. In another aspect of the invention, a method of fluidmanagement can include distending a body space and maintaining a flowrate of up to 850 ml/min of a distension fluid flow into and out of abody space and thereafter through a filter system 540 capable ofremoving at least 20 ml, 40 ml or 60 ml of blood from the distensionfluid 244.

Referring to FIG. 19 , it can be seen that the filter module 540includes detachable connections between the various fluid flow lines toallow for rapid coupling and de-coupling of the filters and flow lines.More in particular, flow line 555 extending from the tissue resectingprobe 515 has a connector portion 592 that connects to inlet fitting 578in the first filter 546A. Flow line portion 555′ that is intermediatethe filters 546A and 546B has connector portion 596 a that connects tooutlet fitting 596 b in first filter 542A. The outflow end of flow line555′ has connector 598 a that connects to inlet fitting 598 b of thesecond filter 546B. The return flow line 600 that is intermediate thesecond 546B and fluid source 535 has connector portion 602 a thatconnects to outlet fitting 602 b in second first filter 546B. In oneembodiment, at least one check valve 605 is provided in the flow pathintermediate the filters 546A, 546B which for example can be in line555′, connectors 596 a, 598 a or fittings 596 b, 598 b. In FIG. 19 , acheck valve 605 is integrated with the inlet end 608 of the secondfilter 546B. In use, the operation of the system will result insubstantial fluid pressures in the interior of the second filter, andthe check valve 605 allows for de-coupling the first filter withoutescape of pressure and release of fluid media into the environment, forexample, when the tissue resecting procedure is completed and thephysician or nurse wishes to transport the vial 576 and tissue strips225 therein to a different site for biopsy purposes. In general, aone-way valve such as check valve 605 can be provided at one or morelocations in flow lines 555 and 555′ to prevent back flows of pressurethrough line 555 to the resecting device 515. For example, a one-wayvalve 605′, such as a float valve, can be provided at one or morelocations in line 555 or fitting 578 as indicated by the dashed line inFIG. 19 (see also FIGS. 20-21 ). A float valve 605″ can also be providedin line 550 proximate the saline source 535.

In one aspect, a fluid management system comprising a first fluid line550 configured to carry distention fluid 224 from a fluid source 535 toa body space, a second fluid line 555, 555′ and 560 configured to carryfluid from the body space to a first filter 570 and then to a secondfilter 575 and then back to the fluid source 535, an outflow pumpoperatively coupled to the second fluid line and at least one checkvalve 605 in the second fluid line intermediate the first and secondfilters 570 and 575.

In one embodiment, the controller 545 of the fluid management system 500is configured for calculation of a fluid deficit that is measured as adifference between a fluid volume delivered to the body space 502 and afluid volume recovered from the body space during a medical proceduresuch as fibroid removal (see FIGS. 16-19 ). A method of fluid managementin a hysteroscopic procedure comprises providing a distention fluidsource 535 (FIG. 17 ) having a predetermined volume, introducing fluid(e.g., saline) from the source 535 through a first flow line or inflowline 550 into the uterine cavity and through a second flow line oroutflow line 555 out of the cavity into a filter module 540 and througha further portion 600 of the second flow line back to the fluid source535 wherein the interior volume of the first and second flow lines andthe filter module when subtracted from the predetermined volume of thesource 535 equals 2.5 liters or less. The instructions for use then caninclude the requirement that only a single 3 liter saline bag can beused in any fibroid or polyp removal procedure, which in turn willinsure that saline intravasation can never exceed 2.5 liters. In thisvariation, the predetermined volume of the source 535 can be 3.0 liters,as in a standard 3 liter saline bag, and the interior system volume canbe at least 0.5 liters.

FIGS. 20 and 21 are schematic diagrams relating to the integratedoperation of an RF tissue resecting probe 515 of the type describedabove and a fluid management system 500 of the type described above. Ingeneral, the controller 545, RF generator 670 and fluid managementsystem 500 are adapted to provide controlled flows of distention fluidinto and out of a body cavity 502 while maintaining a targeted pressurewithin the body cavity while at the same providing RF energy delivery tothe resecting probe contemporaneous with fluid flows. In one systemembodiment, the system can operate in three different modes, allcontrolled by the controller 545: (i) a diagnostic mode forhysteroscopy, (ii) a resecting treatment mode for tissue resection andextraction; and (iii) and a coagulation treatment mode for tissuecoagulation.

Referring to FIG. 20 , in diagnostic mode, the inflow or infusion pump546A, the outflow or aspiration pump 546B and the pressure sensor 560and monitoring system are all activated. In one embodiment, thetouchscreen 565 on controller 545 has a graphical user interface (GUI)with fluid control settings that can be adjusted by the physician (FIG.16 ). The inflow pump 546A can be toggled ON/OFF by touching the inflowpump button on the GUI. The targeted intra-cavity pressure can be set onthe touchscreen 565, for example from 0 to 150 mmHg or more (FIG. 16 ).

In a method of operation as shown in FIG. 20 , the physician sets atarget intra-cavity pressure on the GUI and then activates the inflowpump 546A which causes a flow of distention fluid 244 through the inflowor infusion line 550 and endoscope 512 into the body cavity 502. In oneembodiment, the inflow pump 546A in diagnostic mode can be actuated onthe touchscreen 565. In the diagnostic mode, the controller 545 isconfigured to not actuate the outflow pump 546B until the set pressureis attained or there is an overpressure condition. Thereafter, in onevariation, the outflow pump 546A will then operate at a fixed rate andthe inflow pump speed can be modulated in response to signals from thepressure sensor to stabilize the pressure around the targeted cavitypressure. The actual intra-cavity pressure measured by the pressuresensor 560 can be displayed on the controller GUI (FIG. 16 ).

In order to stabilize fluid pressure in a body cavity, the controller545 includes a pressure control algorithm that is configured as afeedback control loop. The controller microprocessor reads both theintra-cavity pressure set point and the actual cavity pressure based onsignals from the pressure sensor 560. In response to these twoparameters, the algorithm calculates a delta value signal based on ageneric proportional integral (PI) control algorithm. The delta value issent to a digital to analog converter and fed into a motor amplifierthat drives the inflow pump 546A. The controller algorithm thenminimizes the difference between the set pressure and the actualpressure by adjusting the speed of the inflow (infusion) pump 546A.

In one embodiment, the system further includes an actuator and algorithmfor providing a rapid fluid inflow and fluid outflow for flushing thebody cavity 502, which for example can be an actuator button 672 on afootswitch assembly 675. In this flushing method, the outflow(aspiration) pump 546B is actuated to provide an increased level ofoutflow and then the pressure algorithm modulates the speed of theinflow (infusion) pump 564A to maintain the targeted pressure in thecavity. Thus, in the diagnostic mode, the system can be actuated torapidly flush the body cavity with fluid inflows and outflows while thecontroller algorithm maintains intra-cavity pressure as described above.The flow rate through the system and body cavity can be pre-set at 100ml/min or greater, for example at 200 ml/min or 300 ml/min. In anotherembodiment, the physician may select a rapid flow rate on thetouchscreen from 200 ml/min to 800 ml/min.

In a non-diagnostic or therapeutic resecting mode for resecting tissue,referring to FIG. 21 , the controller 545 delivers radiofrequency energyto the bi-polar electrode arrangement of the probe 515 (see FIGS.12A-12C) to resect tissue and also actuates the two pumps to providefluid inflows and outflows as described above. To operate in theresection mode, the physician can use the touchscreen 565 (FIG. 16 ) toenter a non-diagnostic (therapeutic) mode of operation. Thereafter, afirst pedal 677 a on the footswitch 675 can be used to actuate thesystem in resection mode to resect tissue. Actuation of the first pedal677 a results in the controller contemporaneously: (i) activating theoutflow pump 546B at a fixed speed to provide outflows at a rate of 400ml/min to 850 ml/min; (ii) activating the inflow pump 564A which has arotation speed controlled and modulated by the controller 545 asdescribed above to maintain a targeted pressure in the body cavity;(iii) delivering DC voltage to the motor 525 of the resecting probe 515to reciprocate the resecting sleeve 175; and (iv) delivering RF energyto the bi-polar electrode arrangement of the resecting probe 515. In oneembodiment, the RF generator 670 and controller 545 provide a variableDC voltage from 5-20 volts to the motor 525 of the resecting probe, apeak RF power of 200 watts, and a peak RF voltage of 240 volts at a 148kHz frequency.

In the resection mode, the controller's pressure algorithm operates in adynamic flow condition wherein the outflow of distention fluid 244 fromthe body cavity 502 varies as it will be dependent on the rate of tissueresection and the speed at which resected tissue strips 225 and fluid244 can move through the extraction channel 160. The intra-cavitypressure is maintained at the set pressure by the feedback loop whichoperates in a similar manner as described above when the system operatesin the diagnostic mode. Resected tissue strips 225 are moved through thesystem as described above and extracted from the body cavity and probethrough the outflow line 555. The outflows of fluid carries resectedtissue, blood and other body fluids into the first filter 570 and thenthe second filter 575 as can be seen in FIG. 21 . When the physicianreleases pressure on the first pedal 677 a, the resecting probe 515 isthen de-activated and only the inflow 546A will remain active incontrolling the intra-cavity pressure as described previously.

In the coagulation mode, the controller 545 and controller algorithmactivates the bi-polar electrode arrangement of probe 515 to coagulatetissue and also to intermittently actuate the fluid flow functions asdescribed above. The motor 525 in the probe handle is not activated, andthe resecting sleeve 175 is positioned in an intermediate position inthe window 517 in the outer sleeve 518 (cf. FIG. 12A). The intermediateposition of the resecting sleeve 175 in the window 517 is a defaultposition that occurs each time that DC current to probe motor 525 isterminated.

To initiate operation under the coagulation mode, it is assumed that thephysician has previously selected the non-diagnostic (therapeutic) modeof operation using the touchscreen 565. The physician then can actuate asecond pedal 677 b on the footswitch 675 to coagulate tissue. Actuationof the second pedal 677 b results in the controller contemporaneously:(i) delivering RF energy to the bi-polar electrode arrangement of theresecting probe 515; and (ii) intermittently actuating the inflow andoutflow pumps 546A and 546B to cause a circulating fluid flow whilemaintaining intra-cavity pressure as described above. In one embodiment,the dual pumps operate for 1 to 8 seconds after a continuous interval ofRF energy delivery for greater than 10 seconds. The fluid flow rate canbe from 100 to 600 ml/min. Further, each time the physician terminatesRF energy delivery, the inflow and outflow pumps 546A and 546B can beactivated for 1 to 10 seconds. The intermittent circulating flows in thecoagulation mode are adapted to aid in visualization and further toprevent heating of distention fluid 244 in the body cavity 502 as aresult of the RF energy application. In one embodiment, the RF generator670 and controller 545 provide bi-polar radiofrequency outputs forcoagulation at a peak RF power of 110 watts and a peak voltage of 200volts at a 148 kHz frequency.

In operating the system in any diagnostic or therapeutic mode, thecontroller 545 has an over-pressure protection algorithm in the eventthat pressure exceeds the targeted intra-cavity set pressure. In oneembodiment, if the intra-cavity pressure exceeds the set pressure by apredetermined amount for a pre-selected time interval, then thecontroller 545 can activate the outflow pump 546B at a higher pumpingrate than the inflow pump 546A until the measured fluid pressure in thecavity drops below the set pressure. Optionally, the controller 545 canslow or stop the inflow pump 546A until intra-cavity pressure drops tothe targeted level. In one variation, the pump or pumps can be activatedto reduce intra-cavity pressure if the measured pressure exceeds the setpressure by 5 mmHg for greater than 1 second, 2 seconds or 5 seconds.

Another mechanism for over-pressure protection is provided in the form apressure relief valve 680 as depicted in FIG. 18 . In one variation, thepressure relief valve 680 is coupled the housing 682 of sensor 560 andcommunicates with flow channel 108 b′ in the sensor 560 to allow fluidventing and pressure relief through the sensor body. The pressure reliefvalve 680 can relieve pressure at a suitable pressure greater than 100mm Hg, for example 100 mm Hg, 125 mmHg, 150 mmHg or anotherpredetermined pressure. Thus, if intra-cavity pressure exceeds thetargeted maximum level, the controller 545 provides an algorithm-basedpressure relief mechanism by modulating the pumps while the check-valve680 provides a back-up form of pressure relief (FIG. 18 ). Further, thesystem can include a manual pressure relief valve 688 in a disposablefitting 712 coupled to the endoscope for additional safety redundancy(FIG. 20 ).

In another aspect of the invention, the controller 545 includes analgorithm that is adapted to de-activate a powered resection device inthe event that the actual pressure in the treatment site drops below apredetermined threshold level. The controller 545 is provided withcontinuous signals of actual pressure in the site from the pressuresensor assembly 560 (FIG. 18 ). In one variation, if the actual pressurein the site drops below an allowable threshold pressure level, then thecontroller algorithm can automatically de-activate the motor that drivesa reciprocating or rotating resecting member. In another variation, thecontroller algorithm can de-activate RF energy delivery to the workingend of a resecting device 515 as shown in FIGS. 16-17 . In thisvariation wherein RF energy delivery is de-activated, the algorithm maypermit continued movement of the resecting sleeve 175 for a selectedinterval and then RF may be re-activated after the intra-cavity pressurelevel increases above the predetermined threshold either instantaneouslyor when such pressure exceeds the threshold level for a selectedinterval, for example of 1 to 10 seconds. In another variation, thecontroller algorithm can de-activate both the motor drive and RFdelivery upon a fall in pressure below the threshold pressure level. Thethreshold pressure level in this algorithm can be any predeterminedpressure, for example, 100 mmHg or less, 50 mmHg or less, or 25 mmHg orless. In one variation, the threshold pressure level is set at 15 mmHg.

In one aspect of the invention relating to treating tissue and directlysensing pressure in a body space, a method comprises (i) accessing abody space or potential body space with at least one system componentconfigured to provide an inflow of distention fluid 244 to the space andan outflow of fluid from the space, the at least one component includingan electrosurgical tissue resecting probe, (ii) providing a pressuresensor coupled to the at least one component configured to measureactual pressure in the space, (iii) sensing pressure within the spaceand modulating inflow and outflow rates in response to the sensedpressure to achieve or maintain a pressure set point in the space, and(iv) operating the electrosurgical probe at first RF parameters toresect tissue. The probe can be operated at second RF parameters tocoagulate tissue. The step of modulating the inflow rates can provideinflows between 0 ml/min and 800 ml/min. The pressure set point can bebetween 30 mmHg and 200 mmHg. As described above, the step of sensingpressure is accomplished with a sensor coupled to an independent fluidchannel that is separate from the flow channels carrying the distentionfluid inflows and outflows.

In general, a fibroid treatment system corresponding to the inventioncomprises a controller, an inflow pump operated by the controller andconfigured to provide fluid inflow through a flow path to a patient'suterine cavity, an outflow pump operated by the controller andconfigured to provide fluid outflow through a flow path to the uterinecavity; and a motor driven resecting device operated by the controller.The resecting device comprise an elongate introducer having a tissueextraction channel (190A, 190B in FIG. 6A) therein with a diameter of noless than 2.4 mm and an outer sleeve 170 having a diameter of no morethan 3.8 mm. The resecting device is adapted to remove fibroid tissue ata rate of at least 2 gm/min. In this variation, the controller can beconfigured to actuate the inflow and outflow pumps in response tosignals of fluid pressure in the uterine cavity and to maintain thetarget pressure as described above. More in particular, the signal offluid pressure can be provided by a pressure sensor coupled to a staticfluid column communicating with the uterine cavity. In anothervariation, the controller can be configured to operate the resectingdevice in response to at least one parameter selected from a groupconsisting of an inflow pump speed, an outflow pump speed and signals offluid pressure in the uterine cavity as will be described further below.In another aspect of the invention, a fluid management system 500 andcooperating electrosurgical probe are provided that include an inflowpump 546A configured for providing an inflow of a distention fluid intoa site in a patient's body, a control system configured for operatorselection of at least first and second flow control modes wherein thefirst flow control mode is configured for tissue resection and operatesthe inflow pump to provide a first peak inflow rate and wherein thesecond flow control mode is configured for tissue coagulation andoperates the inflow pump to provide a second peak inflow rate.Typically, the first peak inflow rate is greater than the second peakinflow rate. In one variation, the first peak inflow is 1,000 ml/min,800 ml/min, 600 ml/min or 500 ml/min. The fluid management and proceduresystem include a control system configured for operator-selection of apressure set point at the site. As described above, the fluid managementsystem and controller are configured to operate the inflow pump and anoutflow pump to provide an outflow of distention fluid from the site toachieve or maintain the pressure set point in both the first and secondflow control modes.

Referring to FIGS. 16-21 , a fluid management system 500 of theinvention comprises an inflow pump 546A configured for providing aninflow of a distention fluid 244 into a site in a patient's body and anoutflow pump 546B configured for providing an outflow of fluid from thesite, and a controller 545 configured for operator-selection of at leastfirst, second and third flow control modes wherein the first flowcontrol mode is configured for a diagnostic procedure and provides aninflow rate up to 800 ml/min, wherein the second flow control mode isconfigured for a tissue resection procedure and provides an inflow rateup to 1,000 ml/min, and wherein the third flow control mode isconfigured for a tissue coagulation and provides an inflow rate up to800 ml/min with intermittent outflows at pre-selected time intervals.

Still referring to FIGS. 16-21 , a fluid management and resection systemcorresponding to the invention comprises an elongated assemblyconfigured for accessing and performing a procedure in a site in apatient's body, the system components including an endoscope, a tissueresecting probe, a fluid source and tubing set, inflow and outflow pumpsand a controller wherein the inflow pump is configured for providing aninflow of fluid from the fluid source through a first channel in theassembly to the site, wherein the outflow pump is configured forproviding an outflow of fluid through a second channel in the assemblyfrom the site and wherein the controller is configured forcontemporaneous control of the probe in at least one mode of operationand the inflow and outflow pumps to provide and maintain anoperator-selected pressure set point at the site.

The system further includes a disposable pressure sensor detachablycoupled to a system component, and in one variation, the pressure sensoris operatively coupled to a third channel in the system which typicallyis in the endoscope. In another variation, a pressure sensor isoperatively coupled to the tubing set. Typically, the first channeldescribed above is in the endoscope shaft 524 and the second channel isin the tissue resecting probe 515.

In another aspect of the invention, referring to FIGS. 20-21 , the fluidmanagement system includes a fluid source 535, typically a saline bag,with a sealed outflow port 702 and a inflow line tubing 550 that has aconnector end 705 including at least one barb feature configured topermit said connector end 705 to advance into and spike the outflow port702 but prevents withdrawal of said connector end 705 from the outflowport 702.

In another aspect of the invention, the fluid management system 500(FIGS. 16-17 ) includes controller algorithms that are adapted to detecta significant fluid leak or loss within the system when deployed and inuse in a diagnostic or therapeutic procedure. Such a leak can consist offluid loss anywhere in the fluid path, such as at a connector in theinflow or outflow lines (550, 555) or through the cervical canal aroundthe elongated shaft 524 of the endoscope 512 (see FIG. 17 ).

In order to determine a leak or fluid loss, a controller algorithmcontinuously monitors the input voltage to the motor of the inflow orinfusion pump 546A wherein such input voltage corresponds directly topump speed and thus corresponds to the fluid inflow rate. The algorithmfurther continuously monitors the input voltage to the motor of theoutflow or aspiration pump 546B which corresponds directly the fluidoutflow rate. During such continuous monitoring, if the algorithmdetermines that the inflow pump motor is operating at an input voltage(inflow rate) that exceeds a predetermined threshold voltage level, thena timer is started. The threshold voltage level is a function of the setpressure, the actual intra-cavity pressure and which of the operationalmodes in operation at the time (diagnostic mode, resection mode, etc.).In each of the operational modes, the input voltage of the outflow pump(outflow rate) is different to meet the objectives of each mode. Thus,for each different mode and corresponding outflow rate, a differentthreshold voltage, inflow rate and time interval is used to determine ifthere exists an unwanted fluid loss. In another variation, a controlleralgorithm can detect a leak or fluid loss in the system using a linearfit curve that relates infusion motor voltage to an elapsed timeinterval to signal the leak or fluid loss. This type of algorithm mayallow for faster detection of a fluid loss in operating modes in whichthe inflow pump motor operates at higher speeds, such as in a resectionmode. In other words, the fluid loss could be detected earlier in casesin which there is a higher rate of loss. Test data can be collected tomeasure fluid loss at different motor speeds over a time interval todevelop such a linear fit curve.

If the timer exceeds a pre-selected time interval during which inputvoltage of the inflow pump motor exceeds the predetermined voltagethreshold, the controller then will display a notification warningand/or audible or visual alarm to indicate a leak or fluid loss. Thelength of the pre-selected interval also can vary depending on theseverity of the fluid inflow rate, that is, the input voltage to theinflow pump motor, in any of the system's operating modes. As the inflowrate increases above the nominal inflow rate in any mode, the timeinterval preceding the fluid loss warning or alarm will be decreased. Inone variation, the predetermined voltage threshold level can correspondto inflow rates of at least 25 ml/min, at least 50 ml/min or at least100 ml/min and the pre-selected time interval can be at least 1 second,at least 5 seconds or at least 10 seconds.

In another aspect of the invention, the controller 545 includesalgorithms that are adapted to detect kinks or clogs in the infusiontubing of inflow line 550 or the aspiration tubing of outflow line 555.It is possible for the flexible tubing of either the inflow line 550 oroutflow line 555 to be kinked which may remain temporarily unnoticed bythe physician and the nursing staff. If the inflow line 550 is kinked,the decrease in fluid inflows into the treatment site will result in aloss of pressure in the site and the working space may collapse. A kinkin the outflow line 555 can lead to an unwanted fluid pressure increasein the treatment site.

In order to rapidly detect a kink in the infusion line 550 on thepositive pressure side of the inflow pump 564A, a controller algorithmis adapted to provide a kinked tubing warning if the calculated powerdriving the inflow pump motor exceeds a predetermined value over apre-selected time interval. Such a predetermined value depends on themotor, gear box, pump head, and a predetermined pressure limit. As canbe understood from the above description of the dual pump system, themotor power directly corresponds to the pressure on the positivepressure side of the inflow pump 564A. As the pressure in the inflowtubing increases as a result of a kink or clog in the tubing, thehydraulic load on the pump rollers from the tubing will increase, whichtransfers load to the inflow pump motor. This increase in load on themotor then results in an increase in the current which is required todrive the pump motor at the targeted speed. The controller 545 includesan algorithm for maintaining the pump speed (and corresponding flowrate) at a predetermined level, no matter the load, during use of thefluid management system in its various modes. The power value ismeasured by a controller algorithm, and at the predetermined limit, thealgorithm can (i) display a warning of a blocked fluid flow which canrelate to kinked tubing or a clog in the flow paths or filter 575; (ii)display a message or warning that the molecular filter 575 may beclogged; or (iii) display a message to exchange the filter 575. Thealgorithm can further interrupt the procedure by de-activating the pumps546A, 546B, and/or by de-activating the power to any tissue-resectingdevice 515 in use.

The fluid management system 500 further includes a controller algorithmfor detecting a kink or clog in the outflow line 555 on the negativepressure side of the outflow pump 546B. This kink detection isaccomplished by monitoring the motor voltage of both pump motors. If thesystem is being operated in either the resection mode or diagnosticmode, the algorithm first checks to determine if the outflow pump 546Bis in an ON state, and then checks that voltage applied to the inflowpump 546A. If the motor of inflow pump 546A is operating at a voltagebelow a predetermined threshold level, then a timer is started. Thepredetermined voltage threshold of the inflow pump motor is selectedbased on the expected input motor voltage during the resection anddiagnostic modes. The typical fluid outflow rate from the uterine cavityduring the resection and diagnostic modes is 250 to 500 ml/minute, aflow rate which requires a minimum motor voltage input on the inflowpump motor to maintain pressure. If the outflow from the uterine cavitydecreases or stops as a result of a kink in the outflow line 555, thenthe actual intra-cavity pressure would remain at a relatively staticlevel. In this static condition, the input voltage of the inflow pumpmotor would be below the predetermined threshold input voltage, and assuch, the kink detection timer would be initiated. When the timerexceeds a pre-selected time interval ranging from 5 seconds to 120seconds, the algorithm is adapted to provide a kinked tubing warning.Additionally, the algorithm can interrupt the procedure by de-activatingthe pumps (546A, 546B) and/or by de-activating the power to anyresection device 515 in use.

The fluid management system 500 further includes a controller algorithmfor detecting a kink in the tubing of outflow line 555 on the positivepressure side of the outflow pump 546B. The controller algorithm detectssuch a kink in the outflow line 555 if the measured motor current on themotor driving the outflow pump 546B exceeds a predetermined level. Thepredetermined level again depends on the motor, gear box, pump head, anda predetermined pressure limit. The motor current directly correspondsto the pressure on the positive pressure side of the pump 546B. As thepressure in the tubing increases (as a result of a tubing kink or aclogged filter) the hydraulic load onto the pump rollers from the tubingincreases, which transfers load to the motor. This increase in load tothe motor increases the current required to drive the motor at thetargeted speed and flow rate. As described previously, the controller545 includes an algorithm that maintains the pump speed at apredetermined level during use of the fluid management system in variousmodes. Thus, the kink detection algorithm measures the current thatdrives the outflow pump motor, and at the predetermined current limitover a pre-selected time interval, the algorithm can (i) display awarning of kinked tubing; (ii) display a message or warning that themolecular filter 575 is clogged; or (iii) display a message to exchangethe filter 575. Additionally, the algorithm can automatically interruptthe procedure by de-activating the pumps (546A, 546B) and/or byde-activating the power to any resection device 515 in use in responseto detection of the kinked tubing or clog in a flow path.

In another aspect of the invention, the controller 545 includesalgorithms that are adapted to further control and optimize fluidpressure in a site during a tissue resection interval that uses afeedback control loop to maintain the targeted set pressure. Thefeedback control loop consists of utilizing the pressure sensor 560 tomonitor actual pressure in the site, and then utilizing controlleralgorithms to modulate speeds of both the inflow pump 546A and theoutflow pump 546B (FIG. 21 ). More in particular, when the physicianinitiates tissue resection with a tissue resecting device 515 as shownin FIGS. 16-17 and 21 , the tissue volume interfacing the window 517(FIG. 21 ) will at least partially block the window and thus begin toslow the fluid outflow through the extraction channel 160 in the innersleeve 175. As a result of the reduction in outflow, signals from thepressure sensor 560 to the controller 545 will indicate an increase inactual pressure in the site, which then under previously describedalgorithms will cause a reduction in the input voltage in the inflowpump motor to thus slow down the fluid inflow rate. If the condition ofreduced outflow continues for a first pre-selected time interval, thecontroller algorithm then will recognize that the resecting device isresecting tissue and sends a tissue-engagement signal to the controller.After a subsequent or second pre-selected time interval, the algorithmwill cause the controller 545 to reduce the input voltage of the outflowpump motor (and fluid outflow rate) from a higher voltage level (e.g.,15 to 30 volt range) to a lower voltage (e.g., 5 to 12 volt range) andcontemporaneously will put the inflow pump into a “ready” state. In thisready state, if a sudden decrease in actual pressure in the site weresignaled by the pressure sensor 560, then the algorithm would causedelivery of a maximum voltage (e.g., 30 volts, instead of nominalvoltage) to the inflow pump motor to thus cause the maximum fluid inflowinto the site. Upon such a sudden decrease in pressure, the algorithmthen sends a tissue-disengagement signal to the controller, whichactuates the inflow pump at a maximum voltage as described above. Innormal operating conditions, the nominal inflow pump voltage may be inthe 10 to 20 volt range. The objective of this pressure maintenancealgorithm is to anticipate a sudden decrease in pressure in the sitewhen the window 517 in the resecting device is cleared of tissue whilethe resecting device is operating, or when tissue chips are clearedthrough the extraction channel 160 which then results in a rapidincrease in outflow. The then ongoing decreased outflow pump voltagealso reduces the outflow rate, and the “ready” state of the inflow pumpinsures that when the sudden tissue-clearing condition(tissue-disengagement signal) occurs, the inflow pump 546A is activatedat its maximum voltage and inflow rate to match or exceed the outflowrate which then will prevent any drop in actual pressure in the site.The maximum inflow rate and the reduced outflow rate will continue untilthe targeted set pressure is maintained for a pre-selected interval thatcan range from 0.1 second to 10 seconds.

Another method of operating a fluid management system and RF resectingprobe as depicted in FIGS. 16-21 comprises (i) accessing a site in apatient's body with a distal end of an endoscope and working end of anelectrosurgical probe, (ii) delivering RF energy to the working end toapply energy to tissue at the site, (iii) contemporaneously operating afluid management system to provide a selected rate of a fluid inflow to,and fluid outflow from, the site, (iv) detecting a change of a signal ofan electrical parameter of the probe during operation and in response todetecting said change, switching at least one operational parameter ofsaid fluid management system. Typically, the electrical parameter caninclude at least one of an impedance level, a power level, a voltagelevel and a current level. The operational parameter of the fluidmanagement system that can be modulated includes at least one of a rateof fluid inflow to the site, a rate of fluid outflow through a systemoutflow channel from the site, a positive pressure level incommunication with the fluid inflow channel, a negative pressure levelin communication with the fluid outflow channel, a targeted pressure setpoint at the site and a rate of change of any of the preceding. Inanother variation, the at least one operational parameter can include analgorithm for operating a pressure sensing system configured todetermine fluid pressure at the site. In the method described above, theapplied energy can be adapted to ablate and resect tissue or tocoagulate tissue.

While certain embodiments of the present invention have been describedabove in detail, it will be understood that this description is merelyfor purposes of illustration and the above description of the inventionis not exhaustive. Specific features of the invention are shown in somedrawings and not in others, and this is for convenience only and anyfeature may be combined with another in accordance with the invention. Anumber of variations and alternatives will be apparent to one havingordinary skills in the art. Such alternatives and variations areintended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

The invention claimed is:
 1. A fluid management system, comprising: acontroller; and an inflow pump operated by the controller and adapted toprovide a fluid inflow through a flow path to a site in a patient'sbody; wherein the controller is configured to provide a fluid losssignal in response to inflow pump speed; wherein the controller isconfigured to provide a fluid loss warning if the inflow pump speedexceeds a predetermined level for a pre-selected time interval.
 2. Thefluid management system of claim 1, wherein the controller is furtherconfigured to de-activate the inflow pump if the inflow pump speedexceeds the predetermined level for the pre-selected time interval. 3.The fluid management system of claim 1, wherein the pre-selected timeinterval is at least 1 second.
 4. The fluid management system of claim1, wherein the pre-selected time interval is at least 5 seconds.
 5. Thefluid management system of claim 1, wherein the pre-selected timeinterval is at least 10 seconds.
 6. The fluid management system of claim1, wherein the controller is configured to provide a blocked flowwarning if a calculated power for driving the inflow pump exceeds apredetermined level for a preselected time interval.
 7. The fluidmanagement system of claim 1, further comprising: an outflow pumpoperated by the controller and adapted to provide a fluid outflowthrough a flow path from the site in the patient's body.
 8. The fluidmanagement system of claim 7, wherein the controller is configured toactuate the inflow and outflow pumps in response to signals of fluidpressure in the site.
 9. The fluid management system of claim 7, whereinthe controller is configured and adapted to provide a blocked flowwarning if an input voltage to the inflow pump is below a predeterminedthreshold voltage for a preselected time interval during which theoutflow pump is operating.
 10. A fluid management system, comprising: acontroller including a display; and an inflow pump including a motoroperated by the controller and adapted to provide a fluid inflow througha flow path to a site in a patient's body; wherein the controller isconfigured to continuously monitor input voltage to the motor of theinflow pump; wherein the controller is configured to provide a fluidloss warning signal to the display if the input voltage exceeds apredetermined level for a pre-selected time interval.
 11. The fluidmanagement system of claim 10, wherein the controller is furtherconfigured to de-activate the motor of the inflow pump if the inputvoltage exceeds the predetermined level for the pre-selected timeinterval.
 12. The fluid management system of claim 10, wherein thepre-selected time interval is at least 1 second.
 13. The fluidmanagement system of claim 10, wherein the pre-selected time interval isat least 5 seconds.
 14. The fluid management system of claim 10, whereinthe pre-selected time interval is at least 10 seconds.
 15. The fluidmanagement system of claim 10, further comprising: an outflow pumpoperated by the controller and adapted to provide a fluid outflowthrough a flow path from the site in the patient's body.
 16. The fluidmanagement system of claim 15, wherein the controller is configured toactuate the inflow and outflow pumps in response to signals of fluidpressure in the site.
 17. The fluid management system of claim 15,wherein the controller is configured and adapted to provide a blockedflow warning if an input voltage to the inflow pump is below apredetermined threshold voltage for a preselected time interval duringwhich the outflow pump is operating.